You can get a pair of good multimedia speakers (amp built in) and a Signal Cable connector (I use their silver one) and call it a day. OK, this solution is not that portable, but it will sound a buttload better'n'Bose. The speakers I'd recommend are the Swan M200's which have been reduced by their distributor to $179.00 - which is a downright bargain for what you get. You can order them directly from NewEgg here
Marco
Marco